Embroidery machines have been used for many years. These machines have generally been controlled by a program punched into a paper tape although recently electronic storage means have been deployed. The programs on the paper tape etc. which control the embroidery machines are generally in one of two formats, either a tape data format or a condensed data format. Both of these formats control the position of the work table of the machine plus other special functions such as change thread, start, stop etc.
A so-called tape data format contains the step by step commands which the machine executes, for example, move x axis, four steps; move y axis, minus two steps; stitch; etc. It is the lowest level of information on which a machine can work and is often referred to as low level language as each step to be performed by the machine is encoded on the tape.
A so-called condensed data format is a higher level language of pattern storage. This information contains the necessary parameters from which designs can be generated. This format does not tell the machine how far to move the work table etc. but requires the machine or design computer to generate the actual table movement sequence (incremental steps).
Each embroidery design requires a different program. The programs are generated on a design embroidery machine, a design computer or the like. Often called "punching machines" where the designer programs the design machine to generate the desired design. The program thus produced may be stored in, for example, the form of a punched paper tape or the like. To redesign the embroidery design, for example, to vary the density of the stitches or the size of the design of even the orientation of the design. requires reprograming and producing a new paper tape program for the production machines.
Designs which are generated in a condensed data format can be varied in size and stitch density since the information required for generation of incremental steps is provided in the nature of the condensed data format language, however this type of format is generally provided only on the so called "punching machines" which are used for creating the original designs and is not normally used on production machines.
A tape data format is normally used to drive production machines and generally cannot be varied. However, in recent times, these tape programs are able to be manipulated to provide scaling effects. That is, the size of a given design may be increased or decreased but this scaling is limited in its effect. The scaling is achieved by varying the actual stitch length, that is the incremental value between co-ordinate points is varied thus providing longer stitches or shorter stitches which in turn increase or reduce the size of the design. Even though the design may be scaled the actual number of stitches in the design stays the same. This has the disadvantage that when increasing the size of the design the density of the stitches may not be sufficient to provide adequate coverage by the fill stitches and satin stitches leaving areas where the base material shows through. Also, when decreasing the size of the design the stitches may tend to bunch up causing areas of unsatisfactory quality.
This problem has been overcome by using the condensed data format in which the density is determined by the machine when calculating the required stitch depths, but no machine nor device has previously been able to vary the actual stitch density of a design recorded in a tape data format.